1. Field of Invention
The present invention relates to a technology of composite optical dividing device, suitable for use in the image apparatus to divide into multiple wavelength bands
2. Description of Related Art
The device used in liquid crystal displaying apparatus to mix light is called a color filter (CF). Usually, the transmission lights through three color filters in red, green, and blue are mixed into various colors. The color filter can be fabricated by several different methods, such as color matter dispersion, color dyeing, electro-deposition, printing, and so on.
For massive production, the color matter dispersion is mainly used, but it uses the spin coating and causes the waste of the color photoresist.
Although the electro-deposition method can have large fabrication area in massive production and save the material, the light transparent efficiency is relatively low and can not easily change and match to the requirement of pixels from different customs. U.S. Pat. No. 5,503,732 has provides a method to fabricate the color filter based on electro-deposition method. A transparent electrode circuit is coated on a substrate, and the photolithographic process is performed including steps of light exposure and image development. In other words, the electro-deposition method can have large fabrication area in massive production and save the material. However, the light transparent efficiency is poor and it not easy to have a change to meet the requirement of pixel patterns from different customs.
For the printing method, it has low fabrication cost. However, it has poor reproduction with pixel resolution and pixel location. U.S. Pat. No. 5,201,268 has provides an intaglio printing method for fabricating the color filter. The film thickness is controlled by the trench on the printing plate but it has the disadvantages of poor quality of pixel resolution, smooth surface, and precise control of location. However, since the printing method needs no the photolithographic equipment, the fabrication cost is low in advantage. Taiwan patent I278395 has also provided a surface printing method. However, this surface-printing method has the issue that a texture in concavoconvex pattern exits at the edge of the printing plate. This method is not proper for fabricating into rather small pixels. However, due to no need of photolithographic equipment, the printing method has low fabrication cost.
The dyeing method has better color saturation level but is poor in duration for light and thermal factors. In one of design considerations is not including the dyeing mechanism, so as to avoid the disadvantage of dyeing method.